Re: 50 Hz vs. 60 Hz
Originally posted by wyatt:
not that it really applies here. but most aircraft use 115v 400hz there must be some advantage.
Actually it is very relevant to the question being asked. So here is the answer. The lower in frequency you go, the larger (physical size/weight) the transformers and generators are. The flip side is the higher in frequency you go the more voltage drop you have. 50 and 60 Hz is a good medium between size and voltage loss on a system. For example take 20 Hz. It would be great in terms of voltage drop, almost down to I*R, but the size of the transformer for you house would be the size of you car.
So for aircraft and boats 400 Hz is chosen because a tremendous amount of weight and space savings are gained while the area is small enough the voltage drop does not pose a real problem.
I more tidbit, DC Switch Mode Power Supplies. Before they became available the way DC power was converted was to take line voltage to a transformer at 60 Hz and step it down/up to a usable voltage, rectify it to DC, and filter. This is known a linear DC power supply.
Switch Mode is different. You take line voltage and rectify immediately. Then invert the DC back to an AC signal of say 40, 50, or up to 100 KHz, then run it through a transformer to step the voltage up or down, rectify and filter again at the desired DC voltage. What makes this appealing? Very simple you do not need a large, expensive, and heavy 50-lb @ 60 Hz transformer on the input. You just need a very small, light, and inexpensive 2-lb transformer operating at high frequencies.
[ December 23, 2005, 01:45 PM: Message edited by: dereckbc ]